A great number of ancient marine invertebrate species in the Phyla Bryozoa, Mollusca and Porifera were well established in the earth's oceans over one billion years ago. Certainly such organisms had explored trillions of biosynthetic reactions in their evolutionary chemistry to reach present levels of cellular organization, regulation and defense. Marine sponges have changed minimally in physical appearance for nearly 500 million years, suggesting a very effective chemical evolution in response to changing environmental conditions for at least the time period under consideration. Some recognition of the potential for utilizing biologically potent marine animal constituents was recorded in Egypt about 2,700 BC, and by 200 BC sea hare extracts were being used in Greece for medicinal purposes. Such considerations, combined with the general observation that marine organisms (especially invertebrates and sharks) rarely develop cancer, led to the first systematic investigation of marine animal and plant anticancer constituents.
By 1968 ample evidence had been obtained, based on the U.S. National Cancer Institute's key experimental cancer systems, that certain marine organisms would provide new and structurally novel antineoplastic and/or cytotoxic agents. Analogous considerations suggested that marine organisms could also provide effective new drugs for other severe medical challenges, such as viral diseases. Furthermore, marine organisms were expected to contain potentially useful drug candidates (and biochemical probes) of unprecedented structural types that would have eluded discovery by contemporary techniques of medicinal chemistry. Fortunately, some of these expectations have been realized in the intervening period. Illustrative of these successes are the discoveries of the bryostatins, dolastatins, and cephalostatins by the Cancer Research Institute at Arizona State University, Tempe, Arizona where five members of these remarkable anticancer drug candidates are either now in human clinical trial or preclinical development. See U.S. Pat. Nos. 4,816,444; 4,833,257; 4,873,245 and 4,879,278.
As is well known to those presently engaged in medical research, the time between the isolation of a promising new compound and its availability in the market place takes at least several years in the best case and can take several decades when an entity to finance the tortuous regulatory trail is slow to appear. Consequently, industry, in association with the government, has devised a number of qualifying tests which serve two purposes. One purpose is to eliminate those substances whose results in the qualifiers unequivocally demonstrate that the further expenditure of funds on developing those substances would be economically counterproductive. The second, and more important purpose, is to identify those substances which demonstrate a high likelihood of success and therefore warrant the requisite further investment necessary to obtain the data which is required to meet the various regulatory requirements imposed by those governments which regulate the market place into which such substances will enter.
The present cost of obtaining such data approaches Ten Million Dollars ($10,000,000 U.S.) per substance. Basic economics dictate that such an investment will not be made unless there is a reasonable likelihood that it can be recovered. Absent such an opportunity, there will be no such investment, and without investment, research requisite for the discovery of potentially life saving drugs will stop.
Only two hundred years ago, many diseases ravaged humankind. Many of these diseases have been controlled or eradicated. In the development of the means to treat or control these diseases, work with the appropriate common experimental animals is of critical importance. With the various types of cancers, and with the HIV virus, such work is presently ongoing. The research for the treatment of various types of cancer is coordinated in the United States by the National Cancer Institute (NCI). NCI, as a government entity, has been charged with assisting all anti-cancer research. To establish whether a substance has anti-cancer activity, NCI has established a variety of protocols one of which involves testing the candidate substance against a cell line panel containing 60 human tumor cell lines. This protocol has been verified, and is generally accepted throughout the scientific community. This protocol and the established statistical means of evaluating the results obtained therefrom have been fully described in the literature See Principles & Practice of Oncology PPO Updates, Volume 3, Number 10, October 1989, by Michael R. Boyd, M.D., Ph.D. for an in depth description of the test protocol. The statistical analysis of the values obtained is explained in "Display and Analysis of Patterns of Differential Activity of Drugs Against Human Tumor Cell Lines: Development of Means Graph and COMPARE Algorithm", Journal of the National Cancer Institute Reports Vol. 81, No. 14, Pg. 1088, Jul. 14, 1989, by K. D. Paull et al. Both of these references are incorporated herein by this reference thereto.
The Constitution of the United States (Art. 1, Sec. 8) authorizes Congress to establish the United States Patent and Trademark Office (USPTO) to promote scientific advancement. This obligation can only be fully met when the USPTO accepts current medical and scientific realities in the area of medical research. The cell line identifiers designated by the NCI measure the activity of impairment of human tumor cell growth of a candidate drug. These values demonstrate "utility". The sole right obtained by the grant of Letters Patent is the prevention of others from exploiting the subject matter of the patent. The recognition of antineoplastic activity as statutory utility can aid research in the United States, and prevent the citizens of the United States from being held hostage by foreign governments or foreign corporations, if such research is no longer viable in the United States.
A major component of vigorous efforts for over two decades has been directed at marine sponge antineoplastic and/or cytotoxic biosynthetic products. The present disclosure reports the isolation and structural elucidation of a new, strongly cytotoxic macrolide herein denominated "halistatin 1".